---
title: "CVE-2026-34909: Ubiquiti UniFi OS Path Traversal Vulnerability"
url: https://erroneo.us/security/cve/CVE-2026-34909/
description: "CVE-2026-34909 (Ubiquiti UniFi OS): Exploited in the wild (CISA KEV). A malicious actor with access to the network could exploit a Path Traversal…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-05-22
date_modified: 2026-06-24
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-34909"
kev: true
cvss: 10
epss: 0.01793
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-34909: Ubiquiti UniFi OS Path Traversal Vulnerability

**Signal:** Exploited: patch now if you run it. CISA has confirmed exploitation in the wild. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Yes, if you run Ubiquiti UniFi OS. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2026-06-23, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-06-26 ; treat that as the outer limit, not the target.
- EPSS 1.8% , percentile 78: FIRST’s model estimates a 1.8% chance of exploitation activity in the next 30 days, higher than 78% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.

## What it is

A malicious actor with access to the network could exploit a Path Traversal vulnerability found in UniFi OS devices to access files on the underlying system that could be manipulated to access an underlying account.

## Affected products (CVE record)

- Ubiquiti Inc UniFi OS Server: < 5.0.8
- Ubiquiti Inc Express: < 4.0.14
- Ubiquiti Inc UDM: < 5.1.12
- Ubiquiti Inc UDM-Pro: < 5.1.12
- Ubiquiti Inc UDM-SE: < 5.1.12
- Ubiquiti Inc UDM-Pro-Max: < 5.1.12
- Ubiquiti Inc UDM-Beast: < 5.1.11
- Ubiquiti Inc EFG: < 5.1.12
- Ubiquiti Inc UDW: < 5.1.12
- Ubiquiti Inc UDR: < 5.1.12

## Severity

- hackerone CVSS 3.1: 10 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`

## Exploitation

- CISA KEV: added 2026-06-23; federal due date 2026-06-26. Known ransomware use: Unknown.
- CISA required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
- CISA SSVC assessment: exploitation active , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 1.79% probability of exploitation activity in the next 30 days; percentile 78.

## Sources

- [Listed in CISA KEV notes (community.ui.com)](https://community.ui.com/releases/Security-Advisory-Bulletin-064-064/84811c09-4cf4-42ab-bd61-cc994445963b)
- [CVE.org record CVE-2026-34909](https://www.cve.org/CVERecord?id=CVE-2026-34909)
- [NVD entry CVE-2026-34909](https://nvd.nist.gov/vuln/detail/CVE-2026-34909)
- [CISA Known Exploited Vulnerabilities catalog entry](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-34909)
- [Listed in CISA KEV notes (cisa.gov)](https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk)
- [Listed in CISA KEV notes (cisa.gov)](https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk)
- [pwndefend.com](https://www.pwndefend.com/2026/06/09/cve-2026-34910-exploitation-itw-building-a-botnet-mirai/)

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Source page: https://erroneo.us/security/cve/CVE-2026-34909/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt